1. Field of the Invention
The present invention relates to stable metal nanoparticles and more particularly to a bio-template, such as tobacco mosaic virus (TMV), coated with aniline which provides for a stable platform for deposition of a metal oxide layer having a thickness greater than 20 nm thereby providing for a robust platform for the deposition of metals.
2. Background of the Related Art
The exploitation of biologically derived material for the assembly of micro- and nanoscale devices is a rapidly expanding field. At present the adaptation of biological molecules into nanodevices has generally been used to impart novel functionalities, such as nucleic acid recognition or antigen-antibody binding, for use in pathogen detection and gene surveillance. However, there are an increasing number of reports that investigate the use of select biological substrates as “bio-templates” for the patterning of inorganic materials. In particular, the macromolecular structures of viruses have proven to be useful scaffolds for the self-assembly of two- and three-dimensional nano-scaled structures that can be spatially patterned using genetic and/or chemical methods [1], [2], [3], [4], [5] and [6].
Inorganic deposition onto these bio-templates has been accomplished using a variety of methodologies including chemical cross-linking, genetic engineering, and electroless plating, resulting in the deposition of numerous inorganic compounds including metal particles, silica, metal oxides, and metal sulfides [7], [8], [9] and [10]. Virus-assembled inorganic nanostructures have been fashioned into conductive nanowires, field effect transistors, memory device components, and battery electrodes [11], [12], [13] and [14]. From these studies it is clear that inherent biologically properties of viruses, including self-assembly, genetic programmability and spatial patterning provide a novel scaffold for the assembly of inorganic compounds.
Coating of materials onto the TMV surface has relied on electrostatic interactions in aqueous solvents [8], [12], [17] and [18]. In these instances, the solution pH was adjusted so the charge of the coating particle and that of the biological template were mutually attractive. Recently, two approaches have arisen to modify biological surfaces to increase their reactivity: genetic modifications of the coat protein to generate novel reactive amino acid and peptides [1], [2], [3], [4], [11], [12], [19] and [20], and chemical modifications attaching reactive groups directly to the bio-template [10], [21] and [22]. However, one downside to using a biologically derived template is the lack particle stability at high metal ion concentrations [23]. Template instabilities reduce coating efficiencies, resulting in partial or incomplete metal coatings.
Biologically derived nanotemplates hold the potential to produce novel nanostructures of unique size, shape, and function. However, the inherent instabilities in these templates that give flexibility also inhibits their use in a diverse array of coating strategies, thus limiting their application. As such, it would be advantageous to discover a system and method to provide for a TMV surface having increased stability to overcome the shortcomings of prior art biological templates.